1. Field of the Invention
The present invention relates to an ultrasound probe and a method for manufacturing the ultrasound probe for use in an ultrasound diagnostic apparatus or an ultrasound probe device.
2. Description of the Related Art
An ultrasound probe is a device for transmitting a ultrasound to an object, and then, receiving a reflection wave from an interface having its different acoustic impedances in an object, thereby imaging an inside of the object. Such an ultrasound probe is used for an ultrasound diagnostic apparatus for examining an inside of a human body or an ultrasound probe device or the like for examining an inside of a structure.
Now, a description will be given with respect to an ultrasound probe for use in an ultrasound diagnostic apparatus.
FIG. 4 is a schematic view showing a configuration of a conventional ultrasound probe.
As shown in FIG. 4, this ultrasound probe has a casing 100 gripped by an operator. This casing 100 is formed in a rectangular cylinder shape, and an ultrasound transducer 101 is housed inside the casing.
The ultrasound transducer 101 comprises: a backing member 102; a signal substrate 103; a piezoelectric oscillator 104; a first acoustic matching layer 105; a second acoustic matching layer 106; a GND common electrode 107; and an acoustic lens 108 sequentially from the operator's frontal side. Among them, the signal substrate 103, the piezoelectric oscillator 104, the first acoustic matching layer 105, and the second acoustic matching layer 106 are arrayed with respect to a scanning direction (direction vertical to paper face).
The piezoelectric oscillator 104 generates and detects an ultrasound, and is composed of a piezoelectric material 104a, a GND electrode 104b, and a signal electrode 104c. 
The first acoustic matching layers 105 and the second acoustic matching layers 106 match the acoustic impedances of the piezoelectric oscillator 104 and a subject. On surfaces of each of these layers, electrodes 105a and 106a are formed by means of sputtering, plating and the like. The electrodes 105a and 106a are so called electrode-drawing electrodes and electrically connect the GND electrode 104a of the piezoelectric oscillator 104 to the GND common electrode 107 with each other.
The GND common electrode 107 is made of a sheet shaped metal plate, and commonly uses the electrodes 106a of the second acoustic matching layers 106 divided by arraying.
The acoustic lens 108 enhances resolution of an ultrasound, and slightly protrudes from a distal end aperture portion 100a of the casing 100.
The signal substrate 103 is made of part of a flexible substrate 109, and provides a drive signal to each of the elements of the piezoelectric oscillator 104 divided by arraying.
The GND electrode 104b of the piezoelectric oscillator 104 is electrically connected to a control unit 110 via the electrodes 105a and 106a; the GND common electrode 107; and the flexible substrate 109. In addition, the signal electrode 104c of the piezoelectric oscillator 104 is electrically connected to the control unit 110 via the signal substrate 103 and the flexible substrate 109 (refer to Jpn. Pat. Appln. KOKAI Publication No. 4-347146, for example).
In the case of manufacturing the thus configured ultrasound transducer, the piezoelectric oscillator 104, the first acoustic matching layer 105, and the second acoustic matching layer 106 that have been reshaped in their required sizes and dimensions by means of dicing or the like are prepared, and then, the first and second acoustic matching layers 105 and 106 are sequentially adhered on the GND electrode 104b of the piezoelectric oscillator 104. Then, the signal substrate 103 and the backing member 102 are sequentially adhered on the signal electrode 104c of the piezoelectric oscillator 104, and then, a laminate element composed of these piezoelectric oscillator 104, first and second acoustic matching layers 105 and 106, and signal substrate 103 is arrayed with respect to a scanning direction. Then, the GND common electrode 107 and the acoustic lens 108 are sequentially adhered on the second acoustic matching layers 106, and then, the control unit 110 is electrically connected via the flexible substrate 109. In this manner, an ultrasound transducer 101 is completed.
However, in a conventional ultrasound probe manufacturing method, when the ultrasound transducer has been completed, displacement has sometimes occurred between the piezoelectric oscillator 104 and the first acoustic matching layer 105 or between the first acoustic matching layer 105 and the second acoustic matching layer 106. Therefore, in order to prevent ultrasound transducer 101 from disabling entry into the casing 100 due to this displacement, a margin M is provided in advance to dimensions of the casing 100.
However, there has been a problem that, if the margin M is provided to the dimensions of the casing 100, a subject's contact portion S of the ultrasound probe, i.e., a portion that comes into contact with a subject increases in size, and, when a narrow portion such as a gap between ribs is diagnosed, ultrasound transmission/reception cannot be carried out efficiently.
In addition, when the electrodes 105a and 106a are formed on the surfaces of the first and second acoustic matching layers 105 and 106, if a method is used such that the first and second acoustic matching layers 105 and 106 are exposed to a high temperature as in sputtering or the like, a deformation such as a warping is prone to occur in these matching layers 105 and 106. Therefore, there is a need for selecting a material that is not deformed so much even if it is exposed to a high temperature. As a result, a problem with higher cost has occurred.